Im just moving out and Im about to have a baby boy. I need a computer, but don't have alot of spare money right now. Im looking for advice on what parts to build a computer with so I can upgrade it in a year or so to keep it usefull for more than the next 2 years.

Normally I wouldn't suggest this...
But with the info you just gave...
You would be better off right now in buying a brand name complete system. You could not build anything even close to what you could get for the same money.
you can buy a Dell system with monitor and everything for $450.00 and have a warranty. It could be upgraded a little but it will last you for two years as is and then see what position you are in to building a system..

Damn, I was getting real exited to build one. But I know most of you on here know more than I do.

When you want to build one, do you really just have to order a case, mobo, processor, memory, hd, drives, and put that all together? That seems so simple. Only like 6 pieces to a computer?
(assuming all the pieces are compatible)

In all actuallity, the actual building isn't that hard as long as you take your time and don't try to cut corners. There are certain things that one must do, and proceedures for installing the operating system should really be adhered to as that is where most people get fouled up.
There really isn't that many pieces but knowing what goes where and all is a little bit tricky sometimes. Just depends on the system and how much room that you have to work with.
There are other ways to go about it also.
You could go the "barebones" way where you buy a partly built system from a retailer and then add the other things that you may want.
here is a good example:http://3btech.net/ce645alat64b.html
or this with OS:http://3btech.net/baamdsecosyw.html
in which you can add to what they are offering and see if this might be a better way for you.
I originally suggested the brand name purchase simply because it is hard to compete with them for a full system at the lower end market. In the higher price ranges ...it is a different story.
here are the links to a few of the sites that I use regularly.Safe to do business with and decent prices. Just look thru and you will get a better idea as to prices of components and name brands.http://www.newegg.com/http://3btech.net/index.htmlhttp://www.bestbyteinc.com/default.asphttp://www.directron.com/index.html

unfortunatly I don't think it's really possibly to buy an upgradable system and save money, I mean to upgrade you generally buy say the best motherboard, and save something on the processor. so you can upgrade it later...

What I suggest you do is buy a fairly good system, and don't worry about upgrading it just yet...

For a mother board/processor combination I'd suggest anything from PCchips (as they are cheap) in socket a (because AMD chips are a lot cheaper than intel, certanily in terms of speed you get a whole load more bang per buck)...

I suggest that if you have a choice between a board with onboasrd sound and network etc you get that rather than one without, simply because it'll save you having to buy a seperate card...

the same goes for video, it's be beter to spend an extra tenner for onboard video than an extra 50 buynig a seperate card...

for Ram I'd suggest that this is a corner you can cut a little, 512 is ideal but 256MB will be adequate especially snice this computer is mainlyfor school and internet surfing...

the case is another areas where you can shave a few extra quid from the total...
but a very cheap case, even if you don't like the look of it, it'll be hidding under a desk anyway...

save some money by buying a small CRT monitor, rather than somethin nicer like a large flatscreen monitor...
in fact Ebay might even be the bet place to pick up a monitor...

get cheap headphones rather than nice speakers,

Are you UK or US?
lurks have provided some god US links, but if you need links to UK shops just ask...

Thanks alot for the help guys, I really appreciate it. I am US, by the way.

Last question, how do I know if a cheap case's power supply is enough? I would have no problem buying a 50$ case if I knew the power supply would be okay. Should I be more in the 80 or 100 dollar range? Is there a certain wattage I should look for?